We fly higher

(Benji Jones, National Geographics; 19 september 2018)

The Eurasian wryneck can’t put a spell on you, as people once believed, but it does have a few tricks up its sleeve.

This bird’s motto is fake it till you make it. Or in this case, fake it until the threat of being eaten has passed.

That’s the strategy of Eurasian wrynecks, small brown woodpeckers native to Europe, Africa, and Asia. When spooked, they bend and twist their head from side to side, often while hissing, to imitate a forest snake.

“Whenever you catch a wryneck, they usually wiggle with their neck to imitate some kind of snake,” says Anders Nielsen, a student at the University of Copenhagen, who shot the video at Denmark’s Gedser observatory, where scientists capture wrynecks each summer and apply leg bands to monitor their population.

“Moving its head and throat from side to side … it looks pretty strange.”

Once considered otherworldly and a sign of magical powers, the odd behavior is now known to be a form of self-defense, he says. And it’s something of a genius strategy: If you’re not scary yourself—perhaps, you don’t have sharp talons, quick speed, or a powerful bite—impersonate an animal that’s more terrifying. Why not a snake? (See how snakes, spiders, and other animals fool their prey.)

In the hand of a bird bander, the display might not be so convincing. But shrouded in the shadows of a dark tree cavity, where these birds nest, the disguise is sure to trick stoats, goshawks, and other feather-hungry predators, says Kenn Kaufman, a renowned bird expert and field editor at Audubon magazine.

“If you’re a wryneck sitting inside a cavity, writhing around and looking and sounding like a snake is likely to make just about any predator retreat,” he says. “The more snakelike it looks and sounds, the more effective the defense could be.”

One Weird Woodpecker

Wrynecks are in the woodpecker family, but they don’t exactly fit in—at least at first glance.

For one, they don’t peck wood. Instead, they nest in holes that other species have laboriously excavated for themselves. And unlike their tree-drilling brethren, wrynecks forage on the ground, using exceedingly long tongues to slurp up fat-rich ants. (Related: How woodpeckers can thrive in leafy suburbs.)

But while they don’t look or act like your typical backyard woodpecker, wrynecks share important features with them, including a long, flexible neck packed with muscles. (Related: Why woodpeckers don’t get headaches.)

It’s these underlying woodpecker features that make snake mimicry possible, Kaufman says.

“Even though the wrynecks are not digging holes, they’ve got the woodpecker family characteristics, such as really complex vertebrae,” he says. “Since they’re not pounding on trees, they can put those morphological traits to use in other ways, such as by being contortionists and moving their head in every which way.”

In other words, wrynecks have repurposed their family strengths—which most species use for hammering out homes and digging up grubs—to imitate a snake when they feel threatened. And they did so over thousands of years of evolution that selected for “accidental” snake-like traits, Kaufman says.

“There wasn’t any conscious attempt at the start, like ‘gee, I’ll try to look like this other species,” he says. “Selection is likely favoring wrynecks becoming more and more snake-like, just like in other cases of mimicry.”

And there are plenty of other snake mimics in the animal kingdom. The hawkmoth caterpillar can inflate a serpent head, the mimic octopus has eight limbs that each double as sea snakes, and burrowing owls are known to produce a long, hissing noise. Heck, there are even snakes that imitate snakes.

A Bird for Bewitching

Today, you’d be lucky to spot a wryneck in the woods. They’re elusive, well-camouflaged, and in decline. But centuries ago, its shrill cry might have sent you running.

Due to its odd movements, this humble-looking woodpecker—known then as the jynx bird—was once thought to wield magical, perhaps even evil powers. In fact, that’s where our modern word jinx (“one that brings bad luck”) comes from.

Other sources suggest it was also used for love spells. According to the book Birds: Myth, Lore and Legend, hopeless romantics would nail an open-winged wryneck to a spinning top called an iynx, which they would twirl “amid incantations to excite sexual love.”

Thankfully, that practice has long been retired. But the wryneck’s scientific name, Jynx torquilla (from the Latin torqueo, “to twist”) has forever preserved its spellbinding past and head-turning talent.

(University of East Anglia;23 Aug 2018; Photo Matthew Gardner)

One of the rarest birds in the western hemisphere, the Bahama Nuthatch, has been rediscovered by research teams searching the island of Grand Bahama.

The finding is particularly significant because the species had been feared extinct following the catastrophic damage caused by Hurricane Matthew in 2016, and had not been found in subsequent searches.

But it is feared that there could only be two left — placing the species on the verge of extinction and certainly among the world’s most critically endangered birds.

The Bahama Nuthatch is an endangered species, only known from a small area of native pine forest on Grand Bahama Island, which lies approximately 100 miles off Palm Beach, Florida.

University of East Anglia masters students Matthew Gardner and David Pereira set out on a three-month expedition to find this and other endemic Caribbean pine forest bird species.

They made their way through dense forest with thick ‘poisonwood’ understorey — the layer of vegetation growing beneath the main forest canopy — in what is thought to be one of the most exhaustive searches of the island.

They worked in partnership with Nigel Collar and David Wege from Birdlife International and the Bahamas National Trust, the organisation which works to protect the habitats and species of The Bahama Islands.

Meanwhile a second team of Bahamian students, led by Zeko McKenzie of the University of The Bahamas-North and supported by the American Bird Conservancy, also searched for the bird.

The Bahama Nuthatch has a long bill, a distinctive high-pitched squeaky call, and nests only in mature pine trees. There had been a sharp decline in its population crashing from an estimated 1,800 in 2004 to just 23 being seen in a survey in 2007. The decline likely began in the 1950s due to habitat loss due to timber removal, and more recently due to hurricane damage, storm surges having killed large areas native forest.

Both teams made Nuthatch sightings in May, and the UEA team were lucky enough to capture the elusive bird on film.

“Our researchers looked for the bird across 464 survey points in 34,000 hectares of pine forest. It must have been like looking for a needle in a hay stack. They played out a recording of the bird’s distinctive call in order to attract it.

“As well as searching for the elusive bird, they also collected environmental data to better understand its habitat preferences and surveyed the extent of hurricane and fire damage,” she added.”

Matthew Gardner said: “We were the first to undertake such an exhaustive search through 700km of forest on foot.

“We had been scouring the forest for about six weeks, and had almost lost hope. At that point we’d walked about 400km. Then, I suddenly heard its distinctive call and saw the unmistakable shape of a Nuthatch descending towards me. I shouted with joy, I was ecstatic!”

The UEA team made six Nuthatch sightings in total, and McKenzie’s team independently made five sightings, using different methods, in the same small area of forest — including a sighting of what they believe to be two birds together.

Mr Gardner said: “During three months of intensive searching we made six Bahama Nuthatch sightings. Our search was extremely thorough but we never saw two birds together, so we had thought there might only be one left in existence.”

“The other team have reported seeing two together so that is promising. However, these findings place the species on the verge of extinction and certainly amongst the world’s most critically endangered birds.”

“We also don’t know the sex of the birds. In many cases when birds dwindle to such small numbers, any remaining birds are usually male.”

“The photographs clearly show this distinctive species and cannot be anything else” said Michael Parr, President of American Bird Conservancy and a UEA alumnus.

“Fortunately this is not a hard bird to identify, but it was certainly a hard bird to find,” he added.

The Nuthatch was spotted in a small area known as Lucaya Estates. During the research project, birds were seen and heard in three distinct but nearby locations within this area.

Researcher Zeko McKenzie said: “Although the Bahama Nuthatch has declined precipitously, we are encouraged by the engagement of conservation scientists who are now looking for ways to save and recover the species.”

The UEA team however are less optimistic as the exact drivers of the precipitous decline of the bird are still unclear.

Dr Diana Bell said: “Sadly, we think that the chances of bringing this bird back from the brink of extinction are very slim — due to the very low numbers left, and because we are not sure of the precise drivers for its decline.

“But it is still absolutely crucial that conservation efforts in the native Caribbean pine forest do not lapse as it is such an important habitat for other endemic birds including the Bahama Swallow, Bahama Warbler and Bahama Yellowthroat.

“The habitat is also incredibly important for North American migrants including the Kirtlands Warbler,” she added.

Ellsworth Weir, Grand Bahama Parks Manager at the Bahamas National Trust, said: “It has been a pleasure for The Bahamas National Trust to host both Matthew and David as they conducted this very important research on Grand Bahama.”

“Their work has taken them across the length and breadth of the island in what was likely the most in depth search to be conducted. Their research, which was inclusive of bird and habitat surveys, has helped to answer questions that some residents have been asking for some time.”

“Sadly, we realize now that we are faced with a very dire situation regarding the Bahama Nuthatch. We wouldn’t have realized the extent of the issue without the persistent efforts of David and Matthew.”

(Xiaodan Wang, Fenliang Kuang, Kun Tan and Zhijun M 28 April 2018)

Background

China is one of the countries with abundant waterbird diversity. Over the past decades, China’s waterbirds have suffered increasing threats from direct and indirect human activities. It is important to clarify the population trends of and threats to waterbirds as well as to put forward conservation recommendations.

Methods

We collected data of population trends of a total of 260 waterbird species in China from Wetlands International database. We calculated the number of species with increasing, declining, stable, and unknown trends. We collected threatened levels of waterbirds from the Red List of China’s Vertebrates (2016), which was compiled according to the IUCN criteria of threatened species. Based on literature review, we refined the major threats to the threatened waterbird species in China.

Results

Of the total 260 waterbird species in China, 84 species (32.3%) exhibited declining, 35 species (13.5%) kept stable, and 16 species (6.2%) showed increasing trends. Population trends were unknown for 125 species (48.1%). There was no significant difference in population trends between the migratory (32.4% decline) and resident (31.8% decline) species or among waterbirds distributed exclusively along coasts (28.6% decline), inland (36.6% decline), and both coasts and inland (32.5% decline). A total of 38 species (15.1% of the total) were listed as threatened species and 27 species (10.8% of the total) Near Threatened species. Habitat loss was the major threat to waterbirds, with 32 of the total 38 (84.2%) threatened species being affected. In addition, 73.7% (28 species), 71.1% (27 species), and 57.9% (22 species) of the threatened species were affected by human disturbance, environmental pollution, and illegal hunting, respectively.

Conclusions

We propose recommendations for waterbird conservation, including (1) strengthening conservation of nature wetlands and restoration of degraded wetlands, (2) enhancing public awareness on waterbird conservation, (3) improving the enforcement of Wildlife Protection Law and cracking down on illegal hunting, (4) carrying out long-term waterbird surveys to clarify population dynamics, (5) restoring populations of highly-threatened species through artificial intervention, and (6) promoting international and regional exchanges and cooperation to share information in waterbirds and their conservation.

A total of 38 species (14.6% of the total) have been listed as threatened species, including 6 species (2.4%) being listed as Critically Endangered, 16 species (6.4%) Endangered, and 16 species Vulnerable (6.4%). Another 27 species (10.8%) were listed as Near Threatened (Table 2). In addition, 54 species (21.5%) were not assessed due to data deficiency or their marginal distribution in China. The threatened species were mainly in the Orders of Gruiformes (10 species), Charadriiformes (10 species), Anseriformes (8 species), and Pelecaniformes (8 species). The highest proportion of threatened species was in the Order of Ciconiiformes (40.0%) (Table 3). Although the percentage of threatened waterbird species in China (15.1% of the total) was slightly lower than that the global level (18.8%) (Wetland International 2012), the percentage of non-assessed species in China (21.5%) was much higher than that globally (0.4%).

Whether co-habiting populations belong to the same species is only as tough as figuring out if they interbreed or produce fertile offspring. On the other hand, when populations are geographically separated, biologists often struggle to determine whether they represent different species or merely subspecies. To address the age-long issue, a British bird expert has developed a new universal mathematical formula for determining what is a species.

Nature is replete with examples of identifiable populations known from different continents, mountain ranges, islands or lowland regions. While, traditionally, many of these have been treated as subspecies of widely-ranging species, recent studies relying on molecular biology have shown that many former “subspecies” have in fact been isolated for millions of years, which is long enough for them to have evolved into separate species.

Being a controversial matter in taxonomy — the science of classification — the ability to tell apart different species from subspecies across faunal groups is crucial. Given limited resources for conservation, relevant authorities tend only to be concerned for threatened species, with their efforts rarely extending to subspecies.

Figuring out whether co-habiting populations belong to the same species is only as tough as testing if they can interbreed or produce fertile offspring. However, whenever distinct populations are geographically separated, it is often that taxonomists struggle to determine whether they represent different species or merely subspecies of a more widely ranging species.

British bird expert Thomas Donegan has dedicated much of his life to studying birds in South America, primarily Colombia. To address this age-long issue of “what is a species?,” he applied a variety of statistical tests, based on data derived from bird specimens and sound recordings, to measure differences across over 3000 pairwise comparisons of different variables between populations.

Having analyzed the outcomes of these tests, he developed a new universal formula for determining what can be considered as a species. His study is published in the open-access journal ZooKeys.

Essentially, the equation works by measuring differences for multiple variables between two non-co-occurring populations, and then juxtaposing them to the same results for two related populations which do occur together and evidently belong to different “good” species. If the non-co-occurring pair’s differences exceed those of the good species pair, then the former can be ranked as species. If not, they are subspecies of the same species instead.

The formula builds on existing good taxonomic practices and borrows from optimal aspects of previously proposed mathematical models proposed for assessing species in particular groups, but brought together into a single coherent structure and formula that can be applied to any taxonomic group. It is, however, presented as a benchmark rather than a hard test, to be used together with other data, such as analyses of molecular data.

Thomas hopes that his mathematical formula for species rank assessments will help eliminate some of the subjectivity, regional bias and lumper-splitter conflicts which currently pervade the discipline of taxonomy.

“If this new approach is used, then it should introduce more objectivity to taxonomic science and ultimately mean that limited conservation resources are addressed towards threatened populations which are truly distinct and most deserving of our concern,” he says.

The problem with ranking populations that do not co-occur together was first identified back in 1904. Since then, most approaches to addressing such issues have been subjective or arbitrary or rely heavily upon expert opinion or historical momentum, rather than any objectively defensible or consistent framework.

For example, the American Herring Gull and the European Herring Gull are lumped by some current taxonomic committees into the same species (Herring Gull), or are split into two species by other committees dealing with different regions, simply because relevant experts at those committees have taken different views on the issue.

“For tropical faunas, there are thousands of distinctive populations currently treated as subspecies and which are broadly ignored in conservation activities,” explains Thomas. “Yet, some of these may be of conservation concern. This new framework should help us better to identify and prioritize those situations.”